Actuator mechanism



Dec. 15, 1964 R. N. ABlLD ACTUATOR MECHANISM Filed May 29, 1961 /NVENTOP ROBERT N. ABILD BY Z AGENT 3,16 I ,014 Patented Dec. 1 5, 1 964 v ACTUATOR MECHANISM Robert N. Abild, New Britain, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed May 29, 1961, Ser. No. 113,990

. Claims. (Cl. 60-7) `tated or osc'illated between the full-poison position and the full-reflecting position to 'control the rate of reaction within the reactor. Not only is it necessary to have a fine, positive control over the drums during this normal operation, but it is also necessary to be able to scram,

i.'e., swiftly move the drums to the full-poison position, in

response to an emer-gency signal of overactivity of the reactor.

A number of problems attend this scram operation. Loss of the actuating signal to the drum control system should have the Safety feature of locking the drum in its last normally actuated position, unless a scram signal is received. The scram mechanism must always be in some degree of readiness whenever normal operation of the drum vactuator mechanism occurs, and it is desirable that 'the scram mechanism be at its maximum Operating potential whenever normal operation occurs. Provision must also be made to prevent unintended actuation of the scram mechanism. Furthermore, the extremely swift scram movement of the drum to the poison position can result in serious impact damage when the drum is stopped at the full-poison position unless provision is made for braking drum speed as the drum approaches the fullpoison position.

Accordingly, one feature of this invention is a novel actuator mechanism and method of operation thereof in which a member is normally driven to a desired location between first and second positions and in which the driven member is switfly moved to one of the positions in response to a signal.

driven member and then re-engaged with the driven member, thereby rewinding the spring.

Other features and advantages will be apparent from the specification and cla-ims, and from |the accompanying drawings which illustrate an embodimen-t of the invention.

FIG. 1 is va cross-sectional view of the actuating mechanism of the present invention.

FIG. 2 is a view taken along line 2-2 of FIG. 1.

FIG. 3 'is a view taken along line 3-3 of FIG. 1.

Referring to FIG. l, .the actuating mechanism is contained generally within a housing 10. A gear motor 12, which may be powered and controlled as described in my copending application, Serial No. 111,124, filed May 8, 1961, drives a Worm 14. Worm 14 cooperates With gear 16 to rotate gear 16, and Worm 14 and gear 16 are of the irreversible type so that motion can only be transmitted from Worm 14 lto gear 16. An annular piston 18 is positioned within housing 10 and has an annular sleeve 20 extending therefrom. Latch means 22 connects piston 18 and sleeve 20 to the gear 16, and sleeve 20 is held in splined engagement with gear 16 by the force of spring 24. Piston 18 and sleeve 20 cooperate with housing 10 to form an annular chamber 26. Seal rings 28 serve to prevent leakage from Chamber 26, and a passage 30 is provided in housing 10 for supplying a pressurized fluid to Chamber 26. Spring 24 is grounded on shoulder 32. of ring 34, and ring 34 is in turn fixed to and supported by bearing 36 attached to housing 10.

An annular sleeve 38` is threadably connected to ring 34 .and sleeve 38 is also connected to sleeve 20 by spline 44 on sleeve 38 by means of bolts 46. A sleeve 48 ex- Another feature of this invention is a novel actuator i mechanism and method of operation thereof in which a member is normally driven between first and second positions and in which the driven member and its drive are separated in response to a signal.

Still another feature of this invention is la novel actuator mechanism and method of actuation thereof in which a member is normally driven between first and second positions and in which a signal separates the driven mem-` ber and its driving source thereby releasing stored energy to move the driven member to one of the positions.

Still another feature of .the present invention is a novel actuator mechanism and method of operation thereof in which a member normally driven between two positions is swiftly moved to one of the positions and in which a brake is provided to reduce the speed of the member when it approaches the one position.

Still another feature of this invention is a novel actuating mechanism and method of operation such that loss of the actuation signal leaves the driven member locked in its last normally driven position.

Still another feature of the present invention is a novel actuator mechanism and method of operation thereof in which the energy of a spring connected to and positioned between a driven member and a driving means is released to move the driven member to an extreme of its travel upon disengaging the driv'en member and driving means, and in which the driving means then can be moved to a position corresponding to the extreme position o'f the tends from gear 16 and has 'a necked-down portion 50 thereon. Sleeve 48 fits within sleeve 38 and rests on shoulder 52, and sleeve 48 is capable of rotation relative to sleeve 38. It should be apparent that the weights of gear 16, sleeves 38 and 48, reactor control drum 42, piston 18 and sleeve 20 are all transmitted to and supported by bearing 36 through ring 34 and shoulder 32.

A flatV coil spring 54 extends between sleeve 38 and sleeve 50. The innermost part of spring 54 is bent in a generally radial direction and fits within a groove 56 in sleeve 50, and spring 54 is thereby attached to sleeve 50. The outermost part of spring 54 is also bent in a generally radial dircction and fits within a groove 58 in sleeve 38, and spring 54 is thereby also attached to sleeve 38. Bosses 60 on either side of spring 54 prevent axial movement of spring 54. It should be apparent that when sleeve 50 and sleeve 38 .are moved at the same annular Velocity, spring 54 will be unafiected. However, any relative movement between sleeve 50 and sleeve 38 will either vvind or unwind spring 54.

Referring now to FIG. 2, the details of sprag clutch 62 are shown. The clutch consists of an outer race 64, an inner race 66 and a plurality of engaging elements 68 therebetween. The engaging elements 68 are similar to roller-bearing elements but are flat'tened on two sides to provide high .points 70 and 72. A groove 74 is cut in each end of elements 68, and spiral ring Springs 76 in grooves 74 contact each element 68 and urge each element 68 in a clockwise direction about its own axis so that high points 70 and 72 are kept in contact with outer and inner races 64 and 66, respectively. Any force on outer race 64 tending to urge outer race 64 in a counterclockwise direction with respect to inner race 66 will merely result in outer race 64 sliding past contact elements 68 without any attendant movement of inner race 66. This is so because counterclockwise rotation of outer race 64 will tend to cause counterclockwise rotation of elements 68 to move the high points 70 and ,72 away from outer and inner races 64 and 66, respectively, and present the fiattened portions of contact elements 68 to the outer and inner races. However, any force urging outer race 64 in a clockwise direction with respect to inner race 66 will rotate contact element 68 in a clockwise direction thereby moving high points 70 and 72 into binding coupling engagement with outer race 64 and inner race 66, respectively, thereby causing a corresponding clockwise rotation of inner racc 66.

Referring now to FIG. 1, a sleeve 76 extends from inner race 66 and has a friction disc 80 attached thereto and a friction disc 82 splined thereto. Friction discs 84 and 86 are splined to housing 10, and friction discs 80-86 cooperate to form a friction brake. The discs are loaded together and urged against shoulder 83 by Belleville spring 90 and retainer ring 92. An annular fiange 94 extends from outer race 64 to form part of the retaining structure of the sprag clutch, and an annular disc 96 extends from sleeve 38 to also serve as retaining structure for the sprag clutch. A tooth 98 extends from disc 96. As clockwise rotation of sleeve 38 approaches the extreme position, tooth 90 contacts a tooth 100 depending from outer race 64 to cause clockwise rotation of outer race 64, hence causing clockwise rotation of inner race 66 in the manner described above. i

Holes 95 in each friction disc cooperate to form a continuous passage through the friction brake. In a like manner, holes 97 in sprag clutch members 94 and 96 provide a passage through. the sprag clutch. These holes cooperate with passage 99 in shoulder 88 to provide a continuous fiow passage for-the fiow of cooling fluid through all parts of the actuator mechanism. In the application where a nuclear reactor 110 is used as a heating source for expanding hydrogen propellant in a nuclear rocket, the hydrogen itself can be circulated through the control drum and actuator mechanism as a cooling fluid.

In the normal operation of the device, spring 24 holds sleeve 20 in latched engagement with gear 16. Worm 14 rotates gear 16, and gear 16 in turn drives control drum 42 through latch means 22, sleeve 20, spline 40, and sleeve 30. In the present embodiment, drum 42 is rotated in a counterclockwise direction to move the drum to the fullrefiecting position, and drum 42 is ordinarily oscillated or rotated between the poison and reecting positions in accordance with a signal of programmed reactor activity. During thenormal operation, spring 54 is fully wound and constitut'es a source of stored energy for emergency drum rotation in the event that an emergency condition such as an overactivity excursion occurs in the reactor 110 and it becomes necessary to swiftly move the control drums to the full-poison position. This emergency condition can be sensed by a device such as a Geiger counter 112 which in turn can actuate a valve 116 to deliver a supply of pressurized fluid from pressure source 114 to chamber 26 via conduit 30. The increased pressure in chamber 26 acts on the face of piston 18 and moves piston 18 and sleeve 20 in a downward direction against the force of spring 24, thereby disengaging latch means 22 :and freeing sleeve 20 from gear 16. It will be observed that prior to the disengagement of latch means 22 sleeves 120, 38, 48 and 50 all rotate as a unit. When latch means 22 is disengaged, the irreversible nature of gear 16 and vgear 14 holds sleeve 48 and sleeve 50 in a fixed position, and spring 54 is then released to drive sleeve 38 and control drum 42 quickly in a clockwise direction to the fullpoison position.

A braking mechanism is provided in order to prevent the existence of high impact loads when control drum 42 reaches the full-poison position. As control drum 42, and hence sleeve 38, comes to within approximately of the full-poison position, tooth 98 contacts tooth 100 to produce the coupling action of the sprag clutch by driving outer race 64 of the sprag clutch in a clockwise direction. This clockwise rotation of outer race 64 causes a corresponding clockwise rotation of inner race 66 and sleeve ,94 attached thereto, thus causing friction discs 80 and 82 some degree of counterclockwise rotationof the control drum toward the full-refiecting position. In order to resume normal operation of the actuating mechanism, gear 16 is rotated by woxm 14 in a clockwise direction while the emergency pressure is maintained in chamber 26 to continue the disengagement of latch means 22. Gear 16 rotates in a clockwise direction until it reaches the position corresponding to the full-poison position of drum 42, and the emergency signal is then removed from chamber 26 and spring 24 moves piston 18 and sleeve 20 in an lupward direction to re-engage latch means 22. During the above-described clockwise rotation of gear 16, sleeve 48 and sleeve 50 are rotated relative to sleeve 38 thereby rewinding spring 54. Thus, when the emergency signal is removed from chamber 26, normal operation of the actuating mechanism can he resumed and the mechanism is fully primed for another emergency scram operation.

As normal operation of the actuator mechanism is resumed and control drum 42 is rotated in a countercloclrwise direction toward the full-reflecting position, tooth on the outer race 64 of the sprag clutch is repositioned at a point approximately 15 from the full-poison position to reset the sprag clutch for another scram operation. The structure for accomplishing this repositioning of tooth 100 can best be seen in FIG. 3. A tooth 102 depends from outer race 64 at a point approximately removed from tooth 100. An angle flange 104 of arcuate shape is attached to housing 10 to form a chamber 106 having a spring 108 therein. Clockwise rotation of outer race 64 causes tooth 102 to compress spring 108 during the scram operation of the actuator mechanism. When normal operation is resumed, sleeve 38 and hence disc 96 and tooth 93 are rotated in a counterclockwise direction to remove the contact force between tooth 98 and tooth 100. Spring 108 then expands and repositions outer race 64 at a point approximately 15 from the full-poison position.

It should be observed that the present invention discloses an actuator mechanism for a reactor control drum in which a temporary failure of the normal control mechanism will not leave the control drum free to vibrate or coast to an undesired position. That is, if the control mechanism which operates Worm 14 should temporarily fail, the control drum will remain in the| position it occupied prior to such failure, and only a scram signal will move reactor drum 42 to its poison position. This 'feature produces the decided advantage that a temporary malfunction of the normal reactor drum control will not permit or produce undesirable and unnecessary oscillation of the reactor drum.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. In an actuator mechanism, a driven member, driving means, latch means connecting said driving means and said driven member so that said driving means drives said driven member between first and second positions, a wound spring extending between and supported by said driving means and said driven member when so engaged, means for disengaging said driven member and said driving means, means for holding said driving means stationary when said driven member and said driving means are so dise-ngaged to thereby permit said spring to move said driven member to one of said positions when so disengaged.

2. An actuator mechanism as in claim 1 including means for locking said driving means upon disengagement of said driving means and driven member.

3. An actuator mechansm as in claim 1 including brake means, coupling means attached to said brake means, and means cooperating with said driven member for engagng said coupling to operate said brake means whensaid driven member approaches said one position.

4. An actuating unit including driving means moveable between first and second end positions, pressure actuated means, a latch means normally connecting said pressure actuated means to said driving means, a driven' member, a spline connecting said pressure actuated means to said driven member, means for introducing a pressure to said pressure actuated means for disengaging said pressure actuated means from said driving means, means retaining said driving means stationary when so disengaged, and means for moving said driven member to said second end position when said pressure actuated means is disengaged from said driving means.

5. An actuating unit as in claim 4 in which said moving means includes a spring connected to both said driven member and the driving means.

6. An actuator unit as in claim 4 including brake means for braking said driven member When so disengaged, coup-ling means attached to said brake means, and means actuated by said driven member for engaging said coupling to operate said brake means When said driven member is moved by said moving means to a position near said second end position.

7. An actuator mechanism as in claim 6 including meansv for resetting said coupling means When said drivng means reengages said pressure actuating means and said driven member is moved thereby away from said second end position.

8. An actuating unit including driving means, a piston, a latch means normally connecting said piston to said driving means, a driven member, a spline connecting said piston to said driven member, a wound spring extending between and supported by said driving means and said driven member when said latch means connects 'said driving means and said driven member through said piston and said spring urging said driven member in one direction When said driving means is retained in stationary position, means for introducing a pressure to said piston to disengage said latchfrom said driving member and release the force of said spring, means to retain said driving means in stationary position with said driving member disengaged, a sprag clutch adapted to engage said driven member, brake means attached to said sprag clutch, and means connected to said driven member for engaging said sprag clutch and actuating said brake when said driven member is driven by said spring.

9. In an actuated mechanism, a first means constituting a driving member, second means constituting a driven member, third means constituting a detachable connecting means connecting said first and second means,

`fourtlzi means connected to said first means for actuating said first and second members between first and second positions with said third means attached, fifth means operatively connected to said third means to detach said connecting means and hence disconnect said first and second means, sixth means retaning said first means in stationary position when so disconnected, and seventh means connected to 'said first and second means for rapidly driving said second means so disconnected to one of said positions.

10. In an actuator mechanism, a housing, drive means Within saidhcusing comprising an irreversible worm and gear connected to a first sleeve, a spring 'loaded annular piston concentric with said first sleeve and Within said housing and defining a sealed chamber therewith so that said annular piston may be operated between first and second end positions as pressurized fluid is pumped into said Chamber, latch means connecting said annular piston to said drive means when said annular piston is in said first end position, said latch means being disengaged thereby disconnecting said annular piston and said drive means when said annular piston is in said second end position, driven means moveable between first and second end positions and comprisng a second sleeve concentric with said first sleeve and said annular piston and having a tooth projecting therefrom, spline means connecting said second sleeve to said annular piston so that said drive means can drive said driven means between said first and second end positions when said latch means is engaged, a flat coil spring positioned between and attached to said first and second sleeves so that said spring is wound when said sleeves are moved relatively in a first direction until said spring is lfully wound and further so that said driven means will be driven rapidly by said fully wound spring to said driven means second end position when said latch means is disengaged and said first sleeve is held stationary by said irreversible worm, a sprag clutch having outer and inner races positioned Within said hou'sing and concentric with said second sleeve and having a projection extending from and positioned to engage said tooth on said second sleeve when said driven means nears its second end position, and overlapping friction discs extending between said sprag clutch i and said housing and cooperating to brake the movement of said driven means as said driven means nears said second end position.A

References Cted by the Examiner UNITED STATES PATENTS EDGAR W. GEOGHEGAN, Primary Examiner.

ARTHUR M. HORTON, SAMUEL BOYD, JULIUS E.

WEST, Examiners. 

1. IN AN ACTUATOR MECHANISM, A DRIVEN MEMBER, DRIVING MEANS, LATCH MEANS CONNECTING SAID DRIVING MEANS AND SAID DRIVEN MEMBER SO THAT SAID DRIVING MEANS DRIVES SAID DRIVEN MEMBER BETWEEN FIRST AND SECOND POSITIONS, A WOUND SPRING EXTENDING BETWEEN AND SUPPORTED BY SAID DRIVING MEANS AND SAID DRIVEN MEMBER WHEN SO ENGAGED, MEANS FOR DISENGAGING SAID DRIVEN MEMBER AND SAID DRIVING MEANS, MEANS FOR HOLDING SAID DRIVING MEANS STATIONARY WHEN SAID DRIVEN MEMBER AND SAID DRIVING MEANS ARE SO DISENGAGED TO THEREBY PERMIT SAID SPRING TO MOVE SAID DRIVEN MEMBER TO ONE OF SAID POSITIONS WHEN SO DISENGAGED. 